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Joe Armstrong · 05-10-08, 01:54 AM

Propellers have been well understood since about 1861 in fact writings of that period mention The Franklin having a 19 foot propeller with a 28 foot pitch and the Mersey have a 20 foot propeller with a 29 foot pitch.

The first actions required of a sonarman was to count the turns of the prop and report it. In theory when a propeller with a 30 foot pitch makes one revolution the propeller has travelled 30 feet. It should make sense that a ship at a stand still could spin its prop very fast and hardly move and at a-head full this effect would be less. A well designed propeller would have about a 10% slip and lesser designed propeller could have as much as 30% slip. (or efficiency) Once a ship is at a certain speed and the TPK registered this speed if properly recorded and reported would eventually be placed in the ONI 41 - ?? Ships Identification Book. It was not uncommon for a ship to have only one identified TPK and corresponding speed at late in the war as 1944.

I have built a sound chart and corresponding TPK table that is about 60% accurate in SH4. I can receive contact information and dive to PSD and with 60% accuracy tell you what type of ship and how fast it is going with enough accuracy to start up my attack. I usually run one game at a time only (don’t return to port re-fit and go back out) so my sonar, radar and corresponding navigator are only about 90% accurate on what they give me because they are a little short on rank and medals. With 30% accuracy on TPK and 90 % accuracy from my reporters I am still able to take out the target by just getting a little further ahead. Sometimes just in time and sometimes a wait around, but I am in position early enough to use sonar to accurately set up my shots buy last minute maneuvering.

I would eventually like to see this part of game improved with TPK tables at cruising speed for all targets. Then as long as I am not spotted by the enemy they would hold the speed they were at allowing me to get ahead and then use my instruments to properly set up my shots.

05-10-08, 01:54 AM	#6
Joe Armstrong Swabbie Join Date: Sep 2007 Posts: 9 Downloads: 0 Uploads: 0	TPK Propellers have been well understood since about 1861 in fact writings of that period mention The Franklin having a 19 foot propeller with a 28 foot pitch and the Mersey have a 20 foot propeller with a 29 foot pitch. The first actions required of a sonarman was to count the turns of the prop and report it. In theory when a propeller with a 30 foot pitch makes one revolution the propeller has travelled 30 feet. It should make sense that a ship at a stand still could spin its prop very fast and hardly move and at a-head full this effect would be less. A well designed propeller would have about a 10% slip and lesser designed propeller could have as much as 30% slip. (or efficiency) Once a ship is at a certain speed and the TPK registered this speed if properly recorded and reported would eventually be placed in the ONI 41 - ?? Ships Identification Book. It was not uncommon for a ship to have only one identified TPK and corresponding speed at late in the war as 1944. I have built a sound chart and corresponding TPK table that is about 60% accurate in SH4. I can receive contact information and dive to PSD and with 60% accuracy tell you what type of ship and how fast it is going with enough accuracy to start up my attack. I usually run one game at a time only (don’t return to port re-fit and go back out) so my sonar, radar and corresponding navigator are only about 90% accurate on what they give me because they are a little short on rank and medals. With 30% accuracy on TPK and 90 % accuracy from my reporters I am still able to take out the target by just getting a little further ahead. Sometimes just in time and sometimes a wait around, but I am in position early enough to use sonar to accurately set up my shots buy last minute maneuvering. I would eventually like to see this part of game improved with TPK tables at cruising speed for all targets. Then as long as I am not spotted by the enemy they would hold the speed they were at allowing me to get ahead and then use my instruments to properly set up my shots.